The inventions relate to apparatus for recovering logging tools from a wellbore and, more particularly, to improved, flexible connectors which may, preferably, be in the form of flexible wire rope sinker bar assemblies to replace the known type of rigid sinker bar. When wireline strip over operations are conducted on drilling rigs that utilize top drive systems, potentially serious problems can be encountered when the conventional rigid type sinker bar assemblies are forced to pass around the top drive housing.
Conventional wireline fishing operations are comprised of a number of conventional steps, including:
1. A T-bar clamp is clamped onto the logging line and hung off at the rotary table of the rig. PA0 2. The wireline above the T-bar clamp is cut, and a connector is attached to the end of the cable sticking out of the top of the T-bar clamp assembly. PA0 3. Normally, a rigid sinker bar assembly is attached to the portion of the logging line that is run up and down in the derrick. The typical sinker bar assembly is approximately 20 feet long, and a connector on the lower end of the sinker bar assembly is compatible with a connector on the logging line hung off in the T-bar clamp. PA0 4. Prior to beginning a strip over operation, the sinker bar connector is made-up to the end connector on the logging line hung off in the T-bar clamp. Using the logging winch, tension is applied to the logging line, and the T-bar clamp assembly is removed. PA0 5. The wireline connector assembly is then lowered and positioned near the top of the box connection of the drill pipe hung off in the rotary table. PA0 6. Using a hang-off plate, the lower part of the connector is hung off on top of the box connection. The lower sinker bar connector is disconnected to allow the sinker bar assembly to be raised to the racking board (monkey board) level in the derrick. PA0 7. A stand of drill pipe is then latched into the elevators at the racking board height in the derrick. The sinker bar on the logging line is guided (stabbed) into the top of the stand of drill pipe by the derrickman. Next, the sinker bar is lowered down and out through the bottom end of a stand of drill pipe at the rig floor. PA0 8. The sinker bar assembly is then reattached to the connector on the logging line hung off in the hang-off clamp at the rig floor. PA0 9. Tension is taken on the logging line, and the hang-off clamp is removed. PA0 10. The lower end of the drill pipe stand is slowly lowered over the wireline sinker bar assembly at the rig floor, and the drill pipe connection is made up. PA0 11. Next, the stand of drill pipe is slowly lowered in the hole, stripping over the logging line and sinker bar assembly. Once the drill pipe is hung off in the rotary table, the wireline stripping operation can be continued in this manner until the logging tool is washed over with the fishing tool assembly.
When this type of wireline strip over operation is conducted on drilling rigs that utilize top drive systems, problems can be encountered with rigid sinker bar assemblies. Problems occur because when the top drive approaches the rig floor and the drill pipe is hung off in the rotary table, the rigid sinker bar exits the drill pipe. At this point in the strip over operation, with tension on the wireline, it is necessary for the sinker bar assembly to pass around the outside of the top drive housing. The rigid sinker bar assembly can be put in an overload situation when the sinker bars are forced to bend around the outside of the top drive body. As a result, the threaded connections can fail and this presents a serious safety hazard to rig personnel and also to the wellbore.